The present invention generally relates to metallic wiring films for an electronic component and sputtering processes as film forming methods thereof.
Conventionally, low resistive materials (such as, Al and Cu, or, Mo, Cr, etc.) are used for metallic wiring films of an electronic component. For example, in a TFT (Thin film transistor) liquid crystal displays, a demand to reduce resistance of a wiring electrode increases with the upsizing of panels. Thus, the need to use Al or Cu as low resistive wiring increases.
In the use of Al wiring for TFT, problems occur; such problems include hillock generation in a post-process, diffusion to a foundation Si layer when Al wiring is used as source/drain electrodes, and degradation of contact resistance with a transparent electrode consisting of ITO (indium-tin-oxide). In order to avoid these problems, barrier layers for layering Mo, Cr, and an alloy film that contains these metals as a main component are necessary in the front and rear of the AI wiring.
In contrast, for Cu wiring, Cu has a lower resistive material than Al. For Al wiring, the degradation of contact resistance with an ITO transparent electrode becomes a problem. However, the contact resistance in Cu wiring remains in good condition, because Cu is less likely to be oxidized.
Accordingly, the need to use Cu as the low resistive wiring film increases. However, Cu has a problem of poor adhesiveness to a foundation material (such as, glass or Si) in comparison to other wiring materials and a problem of a diffusion of Cu to a Si layer when Cu is used as source/drain electrodes. Thus, a barrier layer in the interface between the Cu wiring and other layers are necessary to improve the adhesion and to prevent the diffusiveness.
Even for a foundation Cu seed layer for Cu plating used for semiconductors, barrier layers are necessary to prevent the diffusion of TiN, TaN or the like from a diffusion problem in the same manner as mentioned above.
As related patents of metallic wiring films for electronic components including Cu as a main component, the technology in which an element, such as Mo, is added to Cu (JPA No. 2005-158887) and the technology in which nitrogen and oxygen are introduced during a film forming process by sputtering of pure Cu (JPA No. 10-12151) are known. However, both of these technologies have problems of adhesiveness, resistance-reducing, and hillock resistance.
The present invention is intended to solve the above-described problems in the above-discussed prior technologies and provide a method for manufacturing Cu-based wiring films and Cu-based barrier layer films that satisfy low resistance, good contact resistance with an ITO transparent electrode, adhesiveness with a glass and Si, prevention of diffusion to a Si layer when used as source/drain electrodes, and hillock resistance, and excellent film characteristics that are required for these devices.